Summary of work: The BLSA data set of 36 years of experience with the diagnostic tests for diabetes and with outcome variables known to be related to plasma glucose concentration (development of clinical diabetes, coronary heart disease incidence, microalbuminuria, and mortality) is an extensive experience in men and women across the adult age span. We have analyzed these data and have collaborated with Dr. Elizabeth Barrett-Connor of the Rancho Bernardo Study and with Dr. Kathryn Flegal of the NHANES-III Study to examine the applicability of recent ADA and WHO standards to older men and women. All three population studies show that there are serious problems in the comparability of fasting glucose and glucose tolerance data. Discrepancies between diagnoses based upon fasting glucose and glucose tolerance are of increasing seriousness with advancing. A detailed analysis of abnormal glucose tolerance in the Baltimore Longitudinal Study of Aging population of men and women has shown that the earliest detectable abnormality usually occurs much earlier with glucose tolerance testing (GTT) than with measurement solely of the fasting glucose concentration (FPG). In men and women, abnormality on the GTT occurs first 71% and 81% of the time respectively, while the first detectable abnormality occurs first on the FPG in only 8% and 3% respectively. Of great importance is the fact that in those participants in whom the GTT is abnormal first, there is a time delay of 10 yr in men and 8 yr in women before the FPG became abnormal. These data support re-institution of the GTT as a screening test for diabetes. The ADA report had recommended in 1997 that the GTT be discontinued. The prevalence of microalbuminuria (24-hr albumin excretion of 20 to 200 micrograms/min) has been quantified in 474 male and 426 female participants in the Baltimore Longitudinal Study of Aging. Subjects were categorized by their glucose metabolic status based upon fasting plasma glucose, glucose tolerance, and glycated hemoglobin levels. There was a highly statistically significant graded increase in the prevalence of microalbuminuria with increasingly abnormal glucose metabolic status. In women, even in the earliest detectable degree of glucose intolerance (the "impaired" state), albumin excretion was significantly greater that in those with normoglycemia. The NIA is contributing to a study under the primary sponsorship of NIDDK. The Diabetes Prevention Program is in its final intervention year. Ten percent of the randomized participants are age 65 or over, and 20% are 60 yrs of age or older. The ADA revision of diagnostic standards caught the DPP in mid-stream since a small fraction of those already recruited (those with fasting glucose values of 126 to 139 mg/dl) converted to "instant diabetics" at entry. Nevertheless overall recruitment goals of 1000 participants in each of three treatment arms were exceeded.